It's a good idea to chronograph your marker before a day of paintball. Fields will often have this equipment available to you, as part of the entry price. But if you're just playing woodsball someplace else, you should consider having your group go in on a chronograph.
One way to know whether or not a field has chronographs available is with field signs. We carry a variety of signs, including signs that tell you where there are air stations, where goggles are required, where barrel covers are required, or areas where firing is not allowed, including of course signs for chronograph stations.
We also have a variety of referee and team chest protectors or arm bands, so you can tell just looking if you're cleared to take a shot from cover.